The dusky leaf monkeys spend their time moving on high trees and spend their time relaxing and searching for food with together in a troop of 5-20 individuals The newborn duskys clutch on to their mother with their orange or yellow fur and cute pink face for about 6 months until it matures to dark grey.
Dusky leaf monkeys are primarily folivorous (a herbivore specialized in eating leaves) and thrive on consumption of flowers, shoots, seedlings, leaves and fruits.
As dusky leaf monkeys are arboreal, they prefer dwelling on tall trees in dense forests.
They inhabit the islands of Penang, Langkawi and Perhentian Besar. Trachypithecus o. obscurus is mainly found in peninsular Malaysia while other subspecies are found scattered in Thailand and Burma.
An alternative name for the dusky leaf monkey is the spectacled langur, wherein the word langur is derived from a Hindu word which means long-tailed. The “spectacled” name of the monkey is adapted from the rings around the eyes which resemble spectacles or glasses.